Method for detecting calls and corresponding units

ABSTRACT

A method for detecting calls is disclosed. A call request initiated by a calling terminal device is received by an access unit of a called terminal device of a data packet transmission network. An invite message is sent from the access unit to the called terminal device. A 200-OK message from the called terminal device is received by the access device. In the event of a detection request, a detection message is received by the access unit in order to initiate a detection of the calling terminal device. Additionally, a telephone terminal device includes a controller, which responds with a 200-OK to an invite message, the terminal device sends a detection message to the access unit in order to initiate a detection of a calling terminal device. An access unit which automatically stores an identifier of a calling terminal device is also disclosed.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Ser. No. 10/500,408 filedJun. 24, 2004, which is the US National Stage of InternationalApplication No. PCT/DE03/01398, filed Apr. 30, 2003 and claims thebenefit thereof. The International Application claims the benefits ofGerman Patent application No. 10220338.5 DE filed May 7, 2002. All ofthe applications are incorporated by reference herein in their entirety.

FIELD OF INVENTION

The invention relates to a method in which a call request is sent from acalling terminal device by way of a signaling unit to a called terminaldevice in order to enable a data transmission between the terminaldevices. User data is then transmitted between the calling terminaldevice and the called terminal device, call data for example. Forexample, a detection request is sent to the signaling unit from thecalled terminal device during the data transmission or in conjunctionwith the signaling relating to the data transmission. For example, onthe basis of the detection request the signaling unit notes anidentifier for the calling terminal device, for example the identifieris saved, saving of the identifier is initiated or the identifier isoutput on an output unit.

BACKGROUND OF INVENTION

For data transmission networks using circuit-switching, such a method isset down in the ITU-T standard (International TelecommunicationUnion-Telecommunication Standardization Sector)—Q.951.7, “Stage 3description for number identification supplementary services using DSS1: Malicious Call Identification (MCID)”. The performance feature isused in particular in conjunction with the preparation of legalproceedings.

In a data transmission network using circuit-switching the data istransmitted in time channels in accordance with a time-divisionmultiplex method. Before data transmission takes place, the timechannels are through-connected in a connection establishment phase andthen remain reserved for the terminal devices involved in the call forthe duration of the call. The data comprises for example call data orvideo data, such as is produced during a videconferencing session.

With regard to the known method, the identifier is a subscriber numberwhose format is set down in the ITU-T standard E.164. The subscribernumber is the means by which the calling terminal device, in other wordsthe terminal device which transmits the call, can be reached in thecircuit-switched data transmission network.

With regard to the known method, the signaling units are switchingcenters in a public telephone network. The signaling units performsignaling in accordance with a standardized protocol, in particular asper ISUP (Integrated Services digital network—User Part). With regard tothe known method, both terminal devices are always situated in thecircuit-switched data transmission network.

SUMMARY OF INVENTION

The object of the invention is to specify a simple method which servesin particular to extend the application area for the “Detection ofCalls” performance feature. A corresponding terminal device, acorresponding signaling unit and corresponding programs are also to bespecified.

The object relating to the method is achieved by the method steps setdown in independent claims. Developments are set down in the dependentclaims.

With regard to the method according to the invention, the calledterminal device is a terminal device in a data transmission network. Inaddition, the signaling unit performs signaling in accordance with asignaling protocol which has been defined for data transmission in adata transmission network.

In a data packet transmission network the data is transmitted in datapackets which normally have a packet header and a packet body. Thepacket header contains details about the recipient of the data packet.In this way the data packets can be forwarded in the data packettransmission network without any additional requirement to establish aconnection on lower protocol layers. One example of a data packettransmission network is a data packet transmission network operatingaccording to the Internet Protocol, for example the Internet. There arealso other data packet transmission networks, however, such as the ATMnetwork (Asynchronous Transfer Mode) for example, in which the datapackets are also designated as cells.

The following are examples of signaling protocols in data packettransmission networks:

the protocols of the ITU-T H.323 protocol family, in particular theH.225 protocol,

the SIP protocol (Session Initiation Protocol) according to RFC 2543 orRFC 2543bis of the IETF (Internet Engineering Task Force), or

an ATM signaling protocol.

The signaling protocols for data transmission in a data packettransmission network differ considerably from the signaling protocolsfor a circuit-switched data transmission network and have previouslybeen defined largely independently of these signaling protocols.

By using the method according to the invention it is possible to achievethe situation where the “Detection of Calls” performance feature canthen also be employed when the called terminal device is situated in adata packet transmission network. The application area for the“Detection of Calls” performance feature is thus considerably extendedbecause a large proportion of terminal devices are connected to datapacket transmission networks. The proportion of these terminal devicesin the total number of terminal devices in circuit-switched datatransmission networks and in data packet transmission networks continuesto increase.

With regard to a development of the invention, the detection request istransmitted along with a message and/or an information element which hasbeen defined for signaling in the data packet transmission network. Inthe case of the development, a detection request is used which wasrequired to be defined additionally for the relevant signaling protocolof the signaling unit.

With regard to an alternative development, an identifier for the calledterminal device is preferably stored in the signaling unit inconjunction with the “General Detection of Calls” performance feature.Upon arrival of the call request, a check is performed by the signalingunit (44) as to whether the identifier of the terminal device to becalled has been stored. The identifier of the calling terminal device isnoted when the identifier of the terminal device to be called (36) hasbeen stored. Therefore, with regard to this development there is no needto define a separate detection request and to generate this withreference to individual calls.

With regard to a development of the method according to the invention,the identifier is conveyed to the signaling unit in conjunction with thecall request. This action makes it possible to note the identifierwithout it previously needing to have been requested by means of a morecomplex method.

With regard to a next development of the method for detecting calls, thecalling terminal device is a terminal device in a circuit-switched datatransmission network. The identifier of the calling terminal device isrequested as a result of the detection request by the signaling unit byway of a network transition unit (used for signaling purposes) to thecircuit-switched data transmission network with the aid of an identifierrequest. In order to process the identifier request in thecircuit-switched data transmission network a standardized method isemployed, in particular a method in accordance with ITU-T standardQ.731.7, “Stage 3 description for number identification supplementaryservices using Signaling System No. 7: Malicious Call Identification(MCID)”.

As an alternative or in a cumulative manner, a method in accordance withBICC standard (Bearer Independent Call Control) performance feature setTwo (CS2—Capability Set) is used for transmitting the identifierrequest, see ITU-T Q.1902.1 to Q.1902.6. With regard to a nextalternative, the identifier request is transmitted according to theSIP-T protocol (SIP for Telephones) in accordance with RFC 3204 of theIETF (Internet Engineering Task Force).

The use of the aforementioned standards offers the facility wherebyessentially only method steps for requesting the identifier between thenetwork transition unit and the signaling unit still need to beredefined. With regard to conveying the identifier as far as the networktransition unit, it is possible to make use to a large extent orcompletely of methods which have already been defined.

The ISUP standard can also extended such that it is suitable for thesignaling in respect of data transmission from one telephone network byway of a data packet transmission network to another telephone network.This extension can also be used if the one terminal device is situatedin the data packet transmission network.

With regard to another development of the method according to theinvention, the calling terminal device is a terminal device in a datapacket transmission network. The signaling unit or another signalingunit checks the access authorization of the calling terminal device forthe data packet transmission network. Signaling units which perform suchchecks are referred to for example as proxy or gatekeeper. By virtue ofthe check on the access authorization of the calling terminal device,any manipulation of the identifier conveyed by the calling terminaldevice is rendered more difficult. With a high degree of probability,the noted identifier thus matches the actual identifier of the callingterminal device.

With regard to a next development, the detection request is transmittedin an INFO message using the INFO method according to de facto standardRFC 2976 of the IETF. The INFO message is also referred to as a request.A header section of the INFO message or a body section of the INFOmessage contains an information element which serves to uniquelyidentify the detection request, for example an information element“Printout” which is used to request the printout of the identifier inthe signaling unit. This development is based on the already definedINFO message. Only small extensions are thus required in order toimplement the method in signaling units and terminal devices.

With regard to another development, the detection request is transmittedin a message using a method in accordance with an RFC defined for thedetection of calls. The definition of an additional RFC is usefulparticularly in a situation when a plurality of further informationelements are required in conjunction with the method for detectingcalls.

With regard to one embodiment, the occurrence of the message itself isactually the request, with the result that no additional informationelements are contained in the message in order to identify the detectionrequest. Alternatively, however, the message contains in its header orin its body an information element which uniquely identifies thedetection request.

With regard to one development, the following data is also noted inaddition to the identifier of the calling terminal device:

the identifier of the called terminal device,

in the case of a call diversion, the identifiers of all terminal devicesinvolved in the call diversion,

the date and the time of the data transmission,

identifiers for the signaling units involved in the call processing, and

identifiers which are relevant to the transmission of the user data, forexample an IP address and the associated RTP port number (Real TimeProtocol) of the network transition unit 28 and/or the terminal device36.

The “Detection of Calls” performance feature is upgraded by the storageof the additional data.

In addition, the invention relates to a terminal device and a signalingunit which are suitable for executing the method according to theinvention or one of its developments. Furthermore, it concerns programswhich are executed in the terminal device or in the signaling unit andare used for executing the method according to the invention or one ofits developments. Consequently, the aforementioned technical effectsapply to the terminal device, the signaling unit and the programs.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be described in the following withreference to the attached drawings. In the drawings:

FIG. 1 shows units of a telephone network and of the Internet for datatransmission between a telephone and a SIP terminal device and also forthe associated signaling,

FIG. 2 shows units of the Internet for data transmission between two SIPterminal devices and also for the associated signaling, and

FIG. 3 shows messages transferred on the Internet for using the“Detection of a Call” performance feature.

DETAILED DESCRIPTION OF INVENTION

FIG. 1 shows a network transition function 10 between a telephonenetwork 12 and a data packet transmission network 14, the Internet forexample. The telephone network 12 is for example the telephone networkoperated by Deutsche Telekom AG. FIG. 1 shows a telephone 16 of acalling subscriber TlnA, a source switching center 18 and a transitswitching center 20 of the telephone network 12. A subscriber connectionline 22 exists between the terminal device 16 and the source switchingcenter 18.

The source switching center 18 is connected to the transit switchingcenter 20 by way of a PCM-30 transmission path 24. The call data istransmitted in a time channel, and the signaling is carried out inaccordance with the ISUP protocol. The source switching center 18 andthe transit switching center 20 are for example conventional switchingcenters of the EWSD type produced by the company Siemens AG.

A PCM-30 transmission path 26 leads from the transit switching center 20for transmitting the user data to a network transition unit 28 whichprovides a part of the network transition function 10. A signalingconnection 30 exists between the transit switching center 20 and aservice provision computer 32 which likewise provides a part of thenetwork transition function 10. Signaling takes place on the signalingconnection 30 according to the ISUP protocol. The network transitionunit 28 is for example a network transition unit of type hiG 1000 fromthe company SIEMENS AG. The service provision computer 32 is a serviceprovision computer of type hiQ 9200 from the company SIEMENS AG.

The network transition unit 28 takes voice data, which is received in aPCM channel of the transmission path 26, from the PCM channel and packsit into data packets which are forwarded in the data packet transmissionnetwork 14, for example by way of a transmission path 34 which connectsfrom the network transition unit 28 through the data transmissionnetwork 14 to a SIP terminal device 36 belonging to a subscriber TlnB.The terminal device 36 operates according to the SIP protocol, see defacto standard RFC 2543. On the other hand, data packets received fromthe data packet transmission network 14 are unpacked in the networktransition unit 28. The user data contained in the data packets isforwarded in a time channel on the transmission path 26.

The service provision computer 32 controls the network transition unit28 with the aid of the MGCP protocol (Media Gateway Control Protocol),see RFC 2705 of the IETF. Control messages generated in this situationare transmitted by way of a transmission path 40 which passes throughthe Internet for example.

The terminal device 36 has an access unit 44 assigned to it which isalso referred to as a proxy unit. The access unit 44 checks the accessauthorization of the terminal device 36 and makes available SIPservices, in particular the service for providing the “Detection of aCall” performance feature. The access unit 44 is for example an accessunit of type hiQ 6200 from the company SIEMENS AG.

A signaling path 46 exists, for example in a local data transmissionnetwork, between the terminal device 36 and the access unit 44. Messagesare exchanged over the signaling path 46 using the SIP protocol.

On the other hand, between the access unit 44 and a service provisioncomputer 48 there exists a signaling path 50 by way of which signalingmessages are likewise transmitted in accordance with the SIP protocol,for example. The service provision computer 48 is also, for example, aservice provision computer of type hiQ 9200 from the company SIEMENS AG.

Between the two service provision computers 32 and 48 there exists asignaling path 52 over which signaling messages are transmitted inaccordance with the BICC standard (Bearer Independent Call Control). Ifnecessary, a so-called call mediation network node according to the BICCstandard is also included in the signaling path 52.

It is assumed that the subscriber TlnA has already made a malicious callto the subscriber TlnB on one occasion. As a result the subscriber TlnBhas applied to his SIP service provider for the “Detection of a Call onRequest” performance feature to be enabled. The performance feature hasbeen enabled in the access unit 44 for the subscriber TlnB.

In order to provide the “Detection of Calls” performance feature, theaccess unit 44 contains a memory unit 60 in which the acquired data canbe stored permanently, and also a printer 62 which can be used to havethe acquired data printed immediately. The method steps carried out withregard to provision of the “Detection of a Call on Request” performancefeature are described in detail below with reference to FIG. 3.

In addition, FIG. 1 shows a further network transition unit 70 which issituated between the Internet 14 and a telephone network 72 to which theterminal device of a subscriber TlnC is connected. A transmission path74 can be used for the exchange of control messages according to MGCPand is situated between the network transition unit 70 and the serviceprovision computer 48.

FIG. 2 shows the case in which the subscriber TlnA does not use histelephone 16 but uses a SIP terminal device 100 in order to call thesubscriber TlnB. Signaling messages can be transmitted between theterminal device 100 and an access unit 102 by way of a signaling path104 according to the SIP protocol. The access unit 102 is likewise aproxy unit which checks the access authorization of the terminal device100 for the data transmission network 14. The access unit 102 containsthe memory unit 106.

Between the access unit 102 and the access unit 44 there exists asignaling path 108 over which signaling messages are transmittedaccording to the SIP protocol.

FIG. 3 shows messages transmitted in the data transmission network 14when using the “Detection of a Call on Request” performance feature. Themessages described with reference to FIG. 3 are exchanged regardless ofwhether the subscriber TlnA is calling from the telephone 16 or from theSIP terminal device 100. The service provision computer 48 is involvedin the former case, whereas if the subscriber TlnA calls from the SIPterminal device 100 then the access unit 102 is involved.

In FIG. 3, operations which relate to the access unit 44 are representedwith the aid of a time shaft 120. Operations which relate to theterminal device 36 are represented with the aid of a time shaft 122.Later points in time are situated further down than earlier points intime on the time shafts 120 and 122.

When subscriber TlnA calls subscriber TlnB, an Invite message 124 whichcomes from the service provision computer 48 or from the access unit 102is received in the access unit 44 at a time t0. The Invite message 124is processed in the access unit 44 according to the SIP protocol suchthat at a time t2 an Invite message 126 is sent from the access unit 44to the terminal device 36. The Invite message also contains thesubscriber number of the telephone 16 or the Internet address and theport address of the terminal device 100. The subscriber number of thetelephone 16 or the identifier of the terminal device 100 is stored in aworking storage facility in the memory unit 60 for the duration of callprocessing.

In the terminal device 36 the Invite message 126 is likewise processedin accordance with the SIP protocol. According to the protocol, at apoint in time t4 a 200-OK message 128 is sent by the terminal device 36as a confirmation to the access unit 44.

After receiving the message 128, according to the protocol at a point intime t6 the access unit 44 sends a 200-OK message 130 to the serviceprovision computer 48 or to the access unit 102. From the side of theservice provision computer 48 or the access unit 102, according to theprotocol at a point in time t8 an ACK message 132 arrives which servesto confirm that the data transmission connection can be used.

As a result of the message 132, at a point in time t10 the access unit44 sends an ACK message 134 to the terminal device 36 according to theprotocol.

At a point in time t12, the subscribers TlnA and TlnB begin to speak toone another, whereby call data is transmitted between the telephone 16and the terminal device 36 or between the terminal device 100 and theterminal device 36. The subscriber TlnB recognizes the voice of themalicious subscriber TlnA again and presses a function key on histerminal device which is linked to the function “Detection of a Call onRequest”. Thereupon at a point in time t14 the terminal device 36automatically generates an INFO message 136 according to RFC 2976. Themessage 136 contains a user-specific information element “Printout”.

The INFO message 136 is received and evaluated in the access unit 44. Asa result of the information element “Printout”, at a point in time t16the subscriber number of the subscriber TlnA which is known in theaccess unit 44 or the identifier of the terminal device 100 is storedpermanently in a non-volatile memory in the memory unit 60, for examplein a file together with other identifiers which are to be stored forother subscribers or only for the subscriber TlnB in conjunction withthe “Detection of a Call on Request” performance feature. At the sametime, this identifier is printed out on the printer 62. Permanentlymeans that the data also remains noted after the end of the call betweenthe subscriber TlnA and the subscriber TlnB until it is printed out inorder then for example to be used as evidence in legal proceedings.

At a point in time t18, the access unit 44 confirms the INFO message 136with the aid of a 200-OK message 138. The call between the subscribersTlnA and TlnB is then continued, or the subscriber TlnB terminates thecall immediately.

With regard to another embodiment, in place of the INFO message 136 aSIP message “MCID-REG” separately defined for the “Detection of a Callon Request” performance feature is sent. The MCID-REG message alsoresults in the subscriber number of the telephone 16 or the Internetaddress of the terminal device 100 being detected and permanently noted.

In place of the signaling protocol on the transmission paths 40 and 74,the signaling protocol ITU-T H.248 can also be used for example.

In place of the method for data transmission between the telephonenetwork 12 and the Internet 14 described with reference to FIG. 1, adifferent method can also be used, for example the functions of theservice provision computer 48 can also be included amongst thoseprovided by the service provision computer 32.

In place of the method described with reference to FIG. 2, other methodscan likewise be used. For example, further access units can also beincorporated into the signaling between the access units 102 and 44. Theuser data can also be transmitted with the aid of the access units 102,44 or the further access units.

With regard to a further embodiment, the “General Detection of Calls”performance feature is enabled by the service provider for thesubscriber TlnB, for example upon application by the subscriber. Theidentifier of the terminal device 36 is noted in a file. Upon receipt ofa call, the identifier of the terminal device to be called isdetermined. The file is searched for this identifier. If the identifieris contained in the file, then the identifier of the called terminaldevice is noted, for example stored and/or printed. However, if theidentifier is not contained in the file, then the identifier of thecalling terminal device is not permanently noted. The call establishmentis carried out regardless of the result of the check. With regard tothis embodiment, no detection request is required from the subscriberTlnB in order to permanently note the subscriber number of the callingterminal device.

1. A method for detecting calls, comprising: receiving a call request,which is initiated by a calling terminal device, by an access unit of acalled terminal device of a data packet transmission network; sending aninvite message, in accordance with the session initiation protocol, fromthe access unit to the called terminal device, the sending in responseto receiving the call request; receiving a first 200-OK message, inaccordance to the session initiation protocol, by the access device, thefirst 200-OK message sent from the called terminal device in response tothe invite message; and in the event of a detection request, receiving adetection message by the access unit in order to initiate a detection ofthe calling terminal device, the detection message sent by the calledterminal.
 2. The method according to claim 1, further comprising:performing the detection of the calling terminal is done in the accessunit.
 3. The method according to claim 1, further comprising: sending asecond 200-OK message, in accordance to the session initiation protocol,from the access device in the direction of the calling terminal device.4. The method according to claim 1, wherein an identifier of the callingterminal device is stored in a memory, the memory resides in the accessunit or the access unit initiates the storing of memory outside theaccess unit.
 5. The method according to claim 4, wherein the identifieris a subscriber number of the calling terminal device is stored in thememory based on the detection message.
 6. The method according to claim1, wherein the calling terminal device is a terminal device of acircuit-switched data transmission network.
 7. The method according toclaim 1, wherein the access unit checks the access authorization of thecalling terminal device for the data packet transmission network.
 8. Themethod according to claim 4, wherein at least one data selected from thegroup consisting of identifier of the called terminal device, date, andtime-of-day is stored in addition to the identifier of the callingterminal device.
 9. A telephone terminal device for a data packettransmission network, comprising: a controller, which responds to asession-initiation-protocol invite message initiated via a call from acalling terminal device, the response being asession-initiation-protocol 200-OK message, which is sent to an accessunit, wherein in the event of a detection request, the terminal devicesends a detection message to the access unit in order to initiate adetection of the calling terminal device.
 10. An access unit for a datapacket transmission network, comprising: a control unit, whichautomatically stores an identifier of a terminal device calling a calledterminal device.
 11. The access unit according to claim 10, wherein theidentifier is automatically stored after the reception of a detectionmessage.